What are mobile emergency alerts (USA)

Many of us in our area in Minnesota for the fist time received an Amber alert on our mobile phones October 22, 2015 for a missing child. The alert was later cancelled when the vehicle and child was found.
Mobile emergency alerts are sent to your mobile phone by a radio signal. Only government officials can make one of these alerts.
The alert does not need wifi, data plan, text messaging plan, nor GPS (location). It just has to be a newer mobile phone that is turned on in the area the message is sent.
When you receive alert since it is limited in the number of characters (for both transmission reasons and the size of the screen) you  may want to follow up by looking  it up on a smart phone, computer, radio, or tv. and taking action if needed such as finding shelter in a storm.
Also remember if driving, to wait until you pull over or have someone else with you read the message.
You have the ability to turn off Amber alerts which are for missing children and the ability to turn off severe weather messages with most phones or contacting your carrier.
Presidential messages cannot be turned off, however as far as I know there has never been any as of the time I’m writing this post.